The present invention relates generally to document imaging, and more particularly, to a system and method for providing stereoscopic imaging in a portable document format.
Stereoscopic imaging is the process of visually combining at least two images of a scene, taken from slightly different viewpoints, to produce the illusion of three-dimensional depth. This technique relies on the fact that human eyes are spaced some distance apart and do not, therefore, view exactly the same scene. By providing each eye with an image from a different perspective, the viewer""s eyes are tricked into perceiving depth.
Typically, where two distinct perspectives are provided, the component images are referred to as the xe2x80x9cleftxe2x80x9d and xe2x80x9crightxe2x80x9d images. For purposes of clarity, this terminology is used throughout the following discussion. However, those skilled in the art will recognize that more than two viewpoints may be combined to form a stereoscopic image.
Stereoscopic images may be produced by a computer using a variety of techniques. For example, the xe2x80x9canaglyphxe2x80x9d method uses color to encode the left and right components of a stereoscopic image. Thereafter, a viewer wears a special pair of glasses that filters light such that each eye perceives only one of the views.
Similarly, page-flipped stereoscopic imaging is a technique for rapidly switching a display between the right and left views of an image. Again, the viewer wears a special pair of eyeglasses that contains high-speed electronic shutters, typically made with liquid crystal material, which open and close in sync with the images on the display. As in the case of anaglyphs, each eye perceives only one of the component images.
Other stereoscopic imaging techniques have been recently developed that do not require special eyeglasses or headgear. For example, lenticular imaging partitions two or more disparate image views into thin slices and interleaves the slices to form a single image. The interleaved image is then positioned behind a lenticular lens that reconstructs the disparate views such that each eye perceives a different view. Some lenticular displays are implemented by a lenticular lens positioned over a conventional LCD display, as commonly found on computer laptops.
Stereoscopic imaging thus provides a means for communicating three-dimensional information on a two-dimensional computer display, which is advantageous in a number of applications. For example, a radiologist can view a three-dimensional x-ray image in order to better diagnose a patient""s condition.
Concurrently, but independent from the above, the recent explosive growth of the Internet has led to the need for a portable document format, or a document format for reliably exchanging and viewing any electronically-stored document, independent of the environment in which it was created. Currently, one popular format is the Hypertext Markup Language (HTML), which is used extensively by xe2x80x9cweb browsersxe2x80x9d such as Netscape Navigator(trademark) to display simple, on-line documents. As a portable document format, however, the simplicity of HTML is its weakness, since HTML is not well-suited to representing and displaying books and other complex, printed documents.
A more feature-rich document format is Postscript(copyright), developed by Adobe Systems Incorporated. Unlike HTML, Postscript can readily represent complex documents, including books and the like. Moreover, Postscript is supported by numerous standard development tools, and is directly processed by many printers and imagesetters. However, as a portable document format, Postscript""s files are typically larger than HTML files, which is a disadvantage for use over the Internet, and, additionally, are not organized for rapid interactive access.
To provide a document format more ideally suited for on-line use, Adobe Systems developed the xe2x80x9cPortable Document Formatxe2x80x9d (PDF). Sharing the flexibility and power of Postscript, PDF files can be optimized to require substantially less disk space. Moreover, PDF files are configured to permit rapid interactive access.
Adobe Systems provides a number of tools for creating documents in the PDF format, such as PDF Writer(trademark) and Acrobat Distiller(trademark). Moreover, Adobe Systems provides a PDF reader/viewer called Acrobat(trademark), which is freely available on the Internet. With Acrobat(trademark), a user can view a file as it was intended to be displayed, independent of the application software, hardware, and operating system in use.
Despite PDF""s ability to represent a variety of image types, no provision is made in PDF for stereoscopic images. Accordingly, what is needed is a system and method for providing stereoscopic imaging in a portable document format. Moreover, what is needed is a specification for a stereo-enhanced portable document format that is capable of representing a stereoscopic image. What is also needed is a stereo-enhanced portable document format reader for displaying a stereoscopic image. In addition, what is needed is a stereo-enhanced portable document format that may be read and displayed by a non-enhanced reader such as Adobe Acrobat.
The present invention solves the foregoing problems by providing a system and method for representing and displaying a stereoscopic image (204) in a portable document format encoded file (112).
In one aspect of the invention, a computer-implemented method for representing a stereoscopic image (204) in a portable document format encoded file (112) includes receiving at least two component images (110A-B) combinable to form the stereoscopic image (204); encoding the component images (110A-B) in a portable document format; associating each of the component images (110A-B) with a stereoscopic indicator (302); and storing the component images (110A-B) and associated stereoscopic indicators (302) in the encoded file (112).
In another aspect of the invention, a computer implemented method for displaying a stereoscopic image (204) represented in a portable document format encoded file (112) includes identifying in the encoded file (112) at least two component images (110A-B) combinable to create the stereoscopic image (204); combining the component images (110A-B) to create the stereoscopic image (204); and displaying the stereoscopic image (204) on a stereoscopic display device (106).
In yet another aspect of the invention, a system (100) for representing a stereoscopic image (204) in a portable document format encoded file (112) includes a computer-readable medium (108) for storing at least two component images (110A-B) combinable to form the stereoscopic image (204); an encoded file creator (116), coupled to the computer-readable medium (108), for receiving the at least two component images (110A-B), for encoding the component images (110A-B) in a portable document format, for associating each of the component images (110A-B) with a stereoscopic indicator (302), and for storing the component images (110A-B) and associated stereoscopic indicators (302) in the encoded file (112).
In still another aspect of the invention, a system (100) for displaying a-stereoscopic image (204) represented in a portable document format encoded file (112) includes a computer-readable medium (108) for storing the encoded file (112), the encoded file (112) comprising at least two encoded component images (110A-B) combinable to form a stereoscopic image (204), the encoded component images (110A-B) further comprising stereoscopic indicators (302); an encoded file reader (118), coupled to the computer-readable medium (108), for identifying in the encoded file (112), responsive to the stereoscopic indicators (302), the at least two component images (110A-B); a stereoscopic imager (120), coupled to the encoded file reader (118), for combining the component images (110A-B) to create the stereoscopic image (204), and for displaying the stereoscopic image (204) on a stereoscopic display device (106); and an image cache (121), coupled to the encoded file reader (118), for storing a first component image (110A,B) while the encoded file reader (118) locates a second, counterpart component image (110A,B).